/*
 * Copyright 2019 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package geb.collection

import java.util.function.Predicate

class FilteringIterator<T> implements Iterator<T> {

    private final Iterator<T> iterator
    private final Predicate<T> predicate

    private T nextObject
    private boolean nextObjectSet

    FilteringIterator(Iterator<T> iterator, Predicate<T> predicate) {
        this.iterator = iterator
        this.predicate = predicate
    }

    @Override
    boolean hasNext() {
        nextObjectSet || setNextObject()
    }

    @Override
    T next() {
        if (!nextObjectSet && !setNextObject()) {
            throw new NoSuchElementException()
        }
        nextObjectSet = false
        nextObject
    }

    private boolean setNextObject() {
        while (iterator.hasNext()) {
            T object = iterator.next()
            if (predicate.test(object)) {
                nextObject = object
                nextObjectSet = true
                return true
            }
        }
    }

}
